As a side effect of choosing talents for Bear form Cat form receives substantial improvements to Claw while Shred is almost unchanged. By my calculations the talent improvements to Claw are sufficient to make it preferable to unimproved Shred even when behind the target. Could someone please check my reasoning and let me know if I've missed something obvious?
Claw: Does weapon damage +115 and generates one combo point. Costs 40 energy with Ferocity and the total direct damage is increased by 20% by Savage Fury.
Shred: Does 2.25 times weapon damage +180 and generates one combo point. Costs 60 Energy.
Natural Weaponry can be ignored as the percentage effect on both attacks is identical.
Blood Frenzy, although not a bear form talent, is assumed in order to simplify the calculations (the effect is to make critical hits as valuable for combo points as for the direct damage, so the percentage effect of critical hits is the same for both attacks permitting them to be ignored).
Each combo point is considered to be worth 150 damage, the difference in damage done between each rank of Ferocious bite. Using Rip higher values can be argued for, but that would tilt this calculation further in favour of Claw.
For a Druid with 120 base damage in Cat form:
Claw: 1.2 * Base (144) + 1.2 * bonus (138) + combo (150) = 432 damage per claw or 10.8 damage per energy.
Shred: 2.25 * Base (270) + bonus (180) + combo (150) = 600 damage per Shred or 10.0 damage per energy.
Claw: Does weapon damage +115 and generates one combo point. Costs 40 energy with Ferocity and the total direct damage is increased by 20% by Savage Fury.
Shred: Does 2.25 times weapon damage +180 and generates one combo point. Costs 60 Energy.
Natural Weaponry can be ignored as the percentage effect on both attacks is identical.
Blood Frenzy, although not a bear form talent, is assumed in order to simplify the calculations (the effect is to make critical hits as valuable for combo points as for the direct damage, so the percentage effect of critical hits is the same for both attacks permitting them to be ignored).
Each combo point is considered to be worth 150 damage, the difference in damage done between each rank of Ferocious bite. Using Rip higher values can be argued for, but that would tilt this calculation further in favour of Claw.
For a Druid with 120 base damage in Cat form:
Claw: 1.2 * Base (144) + 1.2 * bonus (138) + combo (150) = 432 damage per claw or 10.8 damage per energy.
Shred: 2.25 * Base (270) + bonus (180) + combo (150) = 600 damage per Shred or 10.0 damage per energy.